import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import sun.misc.BASE64Decoder;

import sun.misc.BASE64Encoder;

public class Base64Test {

    public static void main(String[] args) throws Exception{

        File inputFile = new File("src/test.jpg");// 放在src文件夹下 待处理的图片

        String strImg = null;

        if(inputFile.exists()){

            strImg = getImageStr(inputFile);

            System.out.println(inputFile.getPath()+"转换后的字符串:\n"+strImg);

        }

        File outputFile = new File("src/testCopy.jpg");// 即将在src文件夹下 生成的图片

        generateImage(outputFile,strImg);

    }

    /**

     * 图片转化成base64字符串

     * @param inputFile  源图片文件路径

     * @return

     */

    public static String getImageStr(File inputFile) throws Exception{// 将图片文件转化为字节数组字符串，并对其进行Base64编码处理

        InputStream in = null;

        byte[] data = null;

        // 读取图片字节数组

        in = new FileInputStream(inputFile);

        data = new byte[in.available()];

        in.read(data);

        in.close();

        // 对字节数组Base64编码

        BASE64Encoder encoder = new BASE64Encoder();

        return encoder.encode(data);// 返回Base64编码过的字节数组字符串

    }

    /**

     * base64字符串转化成图片

     * @param outputFile 输出目标图片

     * @param imgStr BASE64字符串

     * @return

     */

    public static boolean generateImage( File outputFile ,String imgStr ) throws Exception{ // 对字节数组字符串进行Base64解码并生成图片

        if (imgStr == null) // 图像数据为空

            return false;

//        imgStr =  "";

        BASE64Decoder decoder = new BASE64Decoder();

        try {

            // Base64解码

            byte[] b = decoder.decodeBuffer(imgStr);

            for (int i = 0; i < b.length; ++i) {

                if (b[i] < 0) {// 调整异常数据

                    b[i] += 256;

                }

            }

            // 生成jpg图片

            OutputStream out = new FileOutputStream(outputFile);

            out.write(b);

            out.flush();

            out.close();

            System.out.println("通过BASE64字符串\n"+imgStr+"\n 生成"+outputFile.getPath());

            return true;

        } catch (Exception e) {

            return false;

        }

    }

}

src\test.jpg转换后的BASE64字符串:

iVBORw0KGgoAAAANSUhEUgAAAFoAAAAZAQMAAACLqquDAAAABlBMVEUAAAD///+l2Z/dAAAAY0lE

QVR4nGNgIAOwf0DisDHg5DxA1mPAwMDfAONJANEBJA5DAkwPiAOTYTawYWCG6WF8kAaUYYRZfRio

h1kCicMA46QDjWb+AeVYAy1lg8kwgyywgHKcQQI3oJw0ZHfbMJAIALYtEHx6n3m7AAAAAElFTkSu

QmCC

通过BASE64字符串

iVBORw0KGgoAAAANSUhEUgAAAFoAAAAZAQMAAACLqquDAAAABlBMVEUAAAD///+l2Z/dAAAAY0lE

QVR4nGNgIAOwf0DisDHg5DxA1mPAwMDfAONJANEBJA5DAkwPiAOTYTawYWCG6WF8kAaUYYRZfRio

h1kCicMA46QDjWb+AeVYAy1lg8kwgyywgHKcQQI3oJw0ZHfbMJAIALYtEHx6n3m7AAAAAElFTkSu

QmCC

 生成src\testCopy.jpg